1. Field
Example embodiments relate to photosensing transistors, methods of manufacturing the same, and display panels employing a photosensing transistor.
2. Description of the Related Art
Thin film transistors are widely used in a variety of fields, in particular, as a switching and driving device in a display field. Recently, using a thin film transistor as a photosensing element for an optical touch screen device has been suggested. A touch screen device is a device for directly inputting data on a screen. In other words, when a user's finger, or a stylus (e.g., pen), touches a particular location on a display screen of a touch screen device, a set process is performed using software.
Currently, widely used touch screen devices use a method of directly touching a screen of a display device by using a finger or a pen. However, as the size of a display device increases, a distance between a user and a display device increases and thus it may be difficult to use the direct touch method. An optical touch screen device is a device that performs the same function as a conventional touch screen by sensing light instead of contact by a finger or a pen. The optical touch screen device is expected to be useful not only for communications between a user and a terminal but also for communication between users.
When a photosensing transistor is used in an optical touch screen device and a liquid crystal panel is used as a display panel, input light passes through a polarization film and is incident on a photosensing transistor. A light loss occurs while the light passes through the polarization film. Also, a degree of light loss varies according to an incident angle. Photocurrent is reduced by about 10% with respect to a particular incident angle so that a photosensing transistor may not react to incident light. Thus, there is a demand to study about a solution to improve photosensing efficiency.